Process for the decontamination of mustard gas-contaminated carbon fabric



No Drawing. Application May 9, 1945 7 Serial No. 668,469

6 Claims. (Cl. 252-412) This invention relates to the decontamination of protective' fabrics which have been contaminated by vesicant agents. More particularly this; invention pertains to a Patented Apr. 19,- 195i 2 effective decontamination. My invention therefore can be performed by any composition which will produce a neutral solution of hydrogen peroxide in water.

method of decontaminatingcarbon-containing protective fabric which has been exposed to mustard gas.- I It is an object of this invention to devise a process, for the decontamination of protective clothing, ,which'will effectively and economically remove contamination ,by vesicantgases but which WillIIlOt weaken the fabric.

Further objects willappear'hereinafter.

Inorder to protect personnel and materiel against the action of vesicant agents, various types of protective fabrics have been designed. A recent innovation in this fi'eld has been fabrics impregnated with or coated with activated carbon. When these fabrics have been ex posed to the action of a vesicant, such as mustard gas (ClCH CH SCH CH Cl), they become contaminated by adsorption of the gas and must be decontaminated before theycan behandled byunprotected peresonnel and before they can be reused.

It has long been known that mustard gas can be rendered inactive as a vesicant by reaction with bleaching powder and therefore. it.was attempted to employ a dilute aqueous solution of sodium hypochlorite, such as thatemployed in commercial bleaching of textile fabrics, to decontaminate. carbon-coated protective fabrics which had'been exposedtomustard gas vapor.

A sample'ofcarbon-coated fabric was therefore allowed to adsorb mustard vapor to the point of saturation and was then regenerated by immersion in an aqueous sodium hypochlorite (0.2.percent available chlorine) solution for 15 minutes at room temperature, rinsed with water, antichlored with dilute sulfuric acid, again rinsed with Water and finally dried. Although the material had been completely regenerated it was found after four successive contaminations and decontaminations that the carbon-coated fabric had suffered a material decrease in tensile strength, a condition which wasroccasioned by the repeated applications of sodium hypochlorite and 1 dilute acid followed by drying.

I have discovered that the disadvantage exhibited in the use of sodium hypochlorite can be overcome'when a dilute, aqueous, neutral, solution of hydrogen peroxide,

either per se, or produced in situ, is used as the decontaminating agent. Vesicants are removed effectively without decreasing the tensile strength of the material. The use of hydrogen peroxide in my preferred embodiment has the additional advantage over .bleach solutions in that no rinsing following decontamination and prior to drying.

While I have found, because of the latter advantage, and in the interest of economy, that hydrogen peroxide is to be preferred, other peroxides areoperative and the hydrogen peroxide can be generated in situ to produce A specific example of the preferred method performing my invention is as follows: 7 r

EXAMPLE 1 Samples of carbon-coated fabric were contaminated with mustard gas (HS) by being exposed to mustard gas vapor to the point of saturation. The samples were then placed in a 2.0 percent aqueous solution of neutral hydrogen peroxide at room temperature. The samples were then dried for 5 minutes at 250 deg. F. without rinsing. The protective value of the decontaminated fabric after treatment was not significantly difierent from its initial value, as indicated by the data set forth-in Table 1 below. After nine contamination and decontamination cycles, performed as above, the protective value of the fabric was still not significantly different from its initial value as indicated by the data shown in the table below, and at the end of the 9th regeneration no decrease V in the tensile strength of the fabric could lie-determined.

Table I.Regeneration0f carbon coated protective fabric,

following saturation with HS vapor, by means of neutral hydrogen peroxide Regeneration Procedure:

(a) 21 samples of contaminated fabric (total weight 8.4 grams) lmmersed in 2 liters of 2 per cent hydrogen peroxide. ([1) Decontaminatcd samples driedominutes at 250 F, with no rinsing. (0) Protective value determined by"Spotted Dick procedure. The Spotted Dick test used in testing my fabrics is conducted-as follows: A single drop of liquid mustard is placed in the center oi-a cellophaueddislt (.0015 thick) which in turn is located at'the bottom of a circular depression (0.75 diameter, 0.125 deep) lna solid brass plate. The test; fabric is placed overthe depression. On the test fabric is placed in successive order (1) an alkaline filter paper, and-(2) an indicator paper, dyed with CongoRed and subsequently spotted, through a perforated cellophane sheet, with a tetrachlorethane solution of 1,3,4,6-tetrachloro 7,8-dipheuylglycoluril (saturated at 25 C). The wholeassembly is then held in place by a heavy glass plate. The period required for mustard vapor to'penetrate the fabric and to cause the indicator paper to change in color, is defined as the Penetration Time or the Protective Time.

Number ofRe'generatlon Cycles Sample Number Protective Time-minutes In order to determine the optimum regeneration time, tests were run, in which the fabric samples werer subjected to the action of hydrogen peroxide for 5, 10, 30, 60, and minutes. The results of these tests are given in Table II below and the data indicates that complete regeneration is effected in a relatively short time,

Table II.-Regeneration with hydrogen peroxide effect of time Spotted Dick Protective Value-minutes Regoueratlon Time-minutes 5 10 30 60 120 Mean 64.0 58.5 77.6 78

asch Mixture) which yields a neutral solution of hydrogen peroxide when dissolved in water, and is capable of effectively decontaminating fabrics in a manner comparable to dilute hydrogen peroxide per se, for example.

EXAMPLE 2 Samples of carbon-coated protective fabric contaminated with mustard gas by saturation with mustard vapor were placed in a solution prepared by dissolving 12.6 grams of a 50:50 mixture of sodium perborate monohydrate and sodium dihydrogen phosphate mouohydrate in a 100 cc. of water (equivalent to a 2% solution of H Following decontamination, the residual products of the sodium perborate-sodium dihydrogen phosphate reaction were removed from the fabric by repeated rinsing with water and the decontaminated fabric was dried. This fabric then exhibited protective properties comparable to that of uncontaminated controls as indicated by the data presented in Table ]I[ below.

Table [IL-Regeneration with hydrogen peroxide neutral hydrogen peroxide vs. solution prepared from Kharaschs 50:50 mixture of sodium perborate and sodium dihydrogen phosphate ["Spotted Dick" protective timeminuteSJ Decontaminated Fabrics Uncontaminated Controls Hydrogen Kharasch Peroxide Solution Mean-38 46.9 44.3

The nature of this invention has been broadly outlined above, the preferred embodiments have been described and it will be apparent that certain modifications and additional formulations will suggest themselves to those skilled in the art. Accordingly, it is intended that the foregoing description shall be interpreted as illustrative only and not in a limiting sense.

I claim:

1. A process for decontaminating carbon-coated protective fabric which has been exposed to the action of mustard gas, comprising treating said fabric with a solution of neutral hydrogen peroxide produced in situ by action of water with a dry mixture of sodium perborate monohydrate'and sodium dihydrogen phosphate monohydrate producing neutral hydrogen peroxide in water.

2. A process for decontaminating carbon-coated protective fabric which has been exposed to the action of mustard gas, comprising treating said fabric with a dilute solution of neutral hydrogen peroxide.

3. A process for decontaminating carbon-coated protective fabric which has been exposed to the action of mustard gas, comprising treating said fabric with an aqueous of sodium perborate monohydrate and sodium dihydrogen phosphate monohydrate.

4. A process for decontaminating carbon-coated protective fabric which has been exposed to the action of mustard gas, comprising treating said fabric with a neutral 2 percent aqueous solution of hydrogen peroxide.

5. A process for decontaminating carbon-coated protective fabric which has been exposed to the action of mustard gas, comprising treating said fabric with a neutral 2 percent aqueous solution of hydrogen peroxide at room temperature.

6. A process for decontaminating carbon-coated protective fabric which has been exposed to the action of mustard gas, comprising treating said fabric for at least 5 minutes with a neutral 2 percent aqueous solution of hydrogen peroxide.

References Cited in the file of this patent UNITED STATES PATENTS 916,692 Foregger Mar. 30, 1909 1,160,563 Barrington Nov. 16, 1915 1,353,654 Harrison Sept. 21, 1920 2,054,885 Schroter Sept. 22, 1936 2,394,887 Berl Feb. 12, 1946 2,396,923 Mendelsohn Mar. 19, 1946 2,465,228 Hein Mar. 22, 1949 FOREIGN PATENTS 496,752 Great Britain Dec. 1, 1938 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2.,933 45-3 April 19 1960 Dana Burks Jr.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

@o/lumn LL, line 63 after "-rinsng".insert Ts required 4 column 4 line 23, after "aqueous."- lnser-t solutlon Signed and sealed this 13th day of September 1960.

(SEAL) Attest:

KARL H. AXLINE I ROBERT C. WATSON Attesting Oificer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,933,453 April 19. 1960 Dana Burks Jr:

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

@olumn 1 line 63. after- "rinsing" insert is required column 4 line 23., after "aqueous."- insert solution Signed and sealed this 13th day of September 1960.

(SEAL) Attest:

KARL H. AXLINE: ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

3. A PROCESS FOR DECONTAMINATING CARBON-COATED PROTECTIVE FABRIC WHICH HAS BEEN EXPOSED TO THE ACTION OF MUSTARD GAS, COMPRISING TREATING SAID FABRIC WITH AN AQUEOUS OF SODIUM PERBORATE MONOHYDRATE AND SODIUM DIHYDROGEN PHOSPHATE MONOHYDRATE. 